Encapsulation of Luminescent Guests to Construct Luminescent Metal–Organic Frameworks for Chemical Sensing

Abstract

Metal−organic frameworks (MOFs), which are a class of coordination polymers constructed by metal ions or clusters with organic ligands, have emerged as exciting inorganic−organic hybrid materials with the superiorities of inherent crystallinity, adjustable pore size, clear structure, and high degree of functionalization. The MOFs have attracted much attention to develop good luminescent functional materials due to their inherent luminescent centers of both inorganic and organic photonic units. Furthermore, the pores within MOFs can also be used to encapsulate a large number of luminescent guest species, which provides a broader luminescent property for MOF materials. MOFs possess the incomparable multifunctional advantages of inorganic and organic luminescent materials. A large number of luminescent MOFs (LMOFs) have been synthesized for applications in sensing, white-light-emitting diodes (LED), photocatalysis, biomedicine, etc. This paper reviews the encapsulation of various luminescent guests such as lanthanide ions, dyes, quantum dots, and luminescent complexes in metal−organic frameworks to construct luminous sensors with single-or double-emission centers, as well as the research progress of these sensors in chemical sensing. Finally, the challenges in these fields were outlined and the prospects for future development were put forward.

Recognition and Sequestration of Toxic Inorganic Water Pollutants with Hydrolytically Stable Metal‐Organic Frameworks

“…MOFs, in general, on account of being hybrid architectures can potentially bear two different photonic components, i. e., metal cations and organic ligands [65] . Albeit, sometimes emissive nature of MOFs can stem from the guest molecules inside the porous network serving as lumophores [66] . Typically, LMOFs have their luminescence coming from organic ligand and hence constructing MOFs from ligands bearing extended conjugation can endow photonic properties [67] .…”

Metal–organic framework thin films as versatile chemical sensing materials

“…Indeed, as discussed in section 3, optical sensors have been developed by exploiting host-guest interactions within the MOF, where lanthanide ions or dyes are used as the sensing material within a MOF scaffold. Beyond dyes or ions, sensors can be designed by combining MOFs with other materials that exhibit unique optical 198,199 or physical 200 properties, 201,202 in which MOF pore functionalities tune selectivity and the second material provides the sensing response. Indeed, a range of MOF thin film composite materials have been developed for sensing applications, 203,204 where MOFs have been combined with functional materials such as graphene, 205,206 carbon dots, 100,207 perovskites, 208 polymers, 209,210 biomolecules, 210 quantum dots, 201 and various metal nanoparticles 201,210,211 (Figure 19).…”

Sensing Properties of NH2-MIL-101 Series for Specific Amino Acids via Turn-On Fluorescence

“…MOFs are of high diversity in structures and properties, typically showing advantages of high porosity, high specific surface area, openly accessible functional sites, tunable pore size and high chemical/thermal stability [ 19 ]. Due to these superior features, MOFs have been successfully used in different areas including heterogeneous catalysis [ 20 ], gas adsorption and separation [ 21 , 22 ], chemical sensing [ 23 ], drug delivery [ 24 ], bioimaging [ 25 ], etc. As for the luminescent MOFs, the guest species introduced may interact with the backbones of MOFs and result in the enhancement or suppression of luminescence, thereby enabling the application of luminescent MOFs in chemical sensing [ 26 , 27 ].…”